1. Field of the Invention
The present invention relates to a communication device and a method used in a wireless communication system, and more particularly, to a communication device and method of handling a radio resource control (RRC) connection resume procedure.
2. Description of the Prior Art
When a cell re-selection occurs during a radio resource control (RRC) connection resume procedure, a RRC layer of a user equipment (UE) may stop the RRC connection resume procedure. However, the RRC layer may only inform a NAS layer of the UE that the RRC connection is established unsuccessfully, after the RRC connection resume procedure is stopped. Thus, the NAS layer may consider it as a resume failure and regard the corresponding resume parameter as invalid. As a result, when the NAS layer wants to initiate another NAS procedure, the NAS layer would request the RRC layer to use a RRC connection establishment procedure rather than the RRC connection resume procedure as the resume parameter is regarded as invalid. However, the RRC connection establishment procedure is more inefficient than the RRC connection resume procedure. Thus, communication between the UE and the network cannot be performed efficiently.
Thus, how to handle the RRC connection resume procedure is an important problem to be solved.